Re: [PATCH 3.2 090/152] time: adjtimex: Validate the ADJ_FREQUENCY values

Ben Hutchings
2015-02-18T12:55:06Z

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On Tue, 2015-02-17 at 14:16 +0000, Luis Henriques wrote:
> On Tue, Feb 17, 2015 at 01:46:53AM +0000, Ben Hutchings wrote:
> > 3.2.67-rc1 review patch. If anyone has any objections, please let me know.
> >
>
> John reported a regression with this commit [1]. A fix seems to be
> already available, but since it hasn't been accepted into mainline yet
> I haven't picked this patch for the 3.16 kernel.
>
> [1] https://lists.ubuntu.com/archives/kernel-team/2015-February/053981.html

OK, I'll defer this for now.

Ben.

> Cheers,
> --
> Luís
>
> > ------------------
> >
> > From: Sasha Levin <sasha.levin@oracle.com>
> >
> > commit 5e5aeb4367b450a28f447f6d5ab57d8f2ab16a5f upstream.
> >
> > Verify that the frequency value from userspace is valid and makes sense.
> >
> > Unverified values can cause overflows later on.
> >
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Ingo Molnar <mingo@kernel.org>
> > Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> > [jstultz: Fix up bug for negative values and drop redunent cap check]
> > Signed-off-by: John Stultz <john.stultz@linaro.org>
> > [bwh: Backported to 3.2: adjust context]
> > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> > ---
> > kernel/time/ntp.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > --- a/kernel/time/ntp.c
> > +++ b/kernel/time/ntp.c
> > @@ -608,6 +608,13 @@ int do_adjtimex(struct timex *txc)
> > return -EINVAL;
> > }
> >
> > + if (txc->modes & ADJ_FREQUENCY) {
> > + if (LONG_MIN / PPM_SCALE > txc->freq)
> > + return -EINVAL;
> > + if (LONG_MAX / PPM_SCALE < txc->freq)
> > + return -EINVAL;
> > + }
> > +
> > if (txc->modes & ADJ_SETOFFSET) {
> > struct timespec delta;
> > delta.tv_sec = txc->time.tv_sec;
> >
> > --
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--
Ben Hutchings
To err is human; to really foul things up requires a computer.

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